[er455]

Originally Posted by JLMounce

Those pics are better. It doesn't look as bad, but it really looks like this thing is first necking down to a 3" diameter before splitting into two. So instead of going from an area of 9 sq" into a theoretical area of 18 sp", you actually neck down first to a 3" pipe at around 7 sq" of volume, before the transition to 2 pipes.

It's something to take a look at for sure. It's connected with a v band to your down-pipe. Try disconnecting the back of the exhaust and take the car out to see how it feels. If it wakes up, you know you've found at least part of your issue.

Good idea , I get the new balancer Tommorow and I am hoping that’s the old has slipped or was built with the timing marks off , I have read that the older professional products balancer had these issues Thanks

[n2ogpsj462]

That merge sure looks like its choking the hell out of it. I also used the flowmaster scavenger series 4" to dual 3". Also used a flowmaster merge from dual 2.5 to 3.5 into my turbo. Theyre nice pieces

[blueghoast]

Originally Posted by Tom Vaught

Look at it this way:
Naturally aspirated the pressure going into the engine is 14.7 (sea level conditions for this example) psi.
The Pontiac distributor has a vacuum can that adds say 10-12 degrees of additional timing under light load/cruising conditions. So if you have 32 degrees of Initial and Centrifugal timing under a light load cruise condition you could have 40 or 42 degrees of timing in the engine.
(THIS IS JUST AN EXAMPLE OF HOW IGNITION TIMING WORKS)

So you add more load to the engine quickly and two things happen. 1) the load on the engine is higher so the vacuum in the intake manifold drops (dropping the vacuum in the "timing advance vacuum can" on the distributor) and the 42 degrees of total timing goes very quickly back to 32 degrees of timing.
You did not hurt the engine by doing this. It happens thousands of times in a month of driving on the street with a Pontiac stock ignition system.

So now you want to remove 8 degrees of timing at 4500 rpm. 8 degrees of timing removed would make your engine less fuel efficient but happier under the higher load condition with less timing.

Unless you are cruising at 4500 rpm on the highway, not likely, you are in an acceleration mode (higher load) so the reduced timing function is a normal situation under higher engine loads.

The question is "When does it seem the "happiest" under that condition".
8 degrees removed, 4 degrees removed, 10 degrees removed? That takes some tuning time to find out as each engine is different.

Read the plugs, play with the timing, and find out what your engine is happy with for the fuel you are using vs the way the engine is built.

JMT (Just my Thoughts on the subject)

Tom V.

Thanks for the explanation makes a little more sense hearing it rather than
thinking it, If that makes any sense LOL Thanks Again.

GT.

[BruceWilkie]

GT
24 initial no advance till 4000 36 degrees total by 4500 rpm, Boost retard 9 degrees by 2 psi.

Basically this is the timing Chevy used on turbo'd corvair. Basically 27 total boosted with initial dropping to 15 at 2 psi and staying there till 4000 before advancing to 27 by 4500.

[er455]

Ok so I replaced the old Professional Products balancer which had 3/8 “ of play on the outer ring back and forth so it has slipped , I put the new balancer on and checked the timing it’s now reading 19 degrees , so I changed the timing to 24 degrees and left the boost at 12 # car feels better . Next is to get the Fitech tuned better. Thanks guys ....

[Tom Vaught]

Like I posted earlier the PP stuff can be real POS parts at times.
You are lucky the outer ring did not come completely off and the crank was then damaged.

Let us know how the other part works out for you.

Tom V.

[er455]

Originally Posted by Tom Vaught

Like I posted earlier the PP stuff can be real POS parts at times.
You are lucky the outer ring did not come completely off and the crank was then damaged.

Let us know how the other part works out for you.

Tom V.

Your right Tom, lesson learned .

[blueghoast]

Originally Posted by er455

Your right Tom, lesson learned .

Sounds like were both learning. I love this sight.

GT.

[blueghoast]

Originally Posted by BruceWilkie

GT
24 initial no advance till 4000 36 degrees total by 4500 rpm, Boost retard 9 degrees by 2 psi.

Basically this is the timing Chevy used on turbo'd corvair. Basically 27 total boosted with initial dropping to 15 at 2 psi and staying there till 4000 before advancing to 27 by 4500.

I just wasn't sure how it would do with making that much timing diff all at once.
I'll try it and let you all how it works. We were sopposed to do a little
street racing tonight but the damb rain won't give us a break.

GT.

[BruceWilkie]

Originally Posted by blueghoast

I just wasn't sure how it would do with making that much timing diff all at once.
I'll try it and let you all how it works. We were sopposed to do a little
street racing tonight but the damb rain won't give us a break.

GT.

Start with less and work your way up . Keep in mind that unboosted your running a low compression motor on premium fuel! !!

Deb's 406 originally had 6x-8 heads. Ran fine even on 85 octane from the reservation pump. On 93 premium it notably felt slower. On 93 advancing to 20 initial brought response back but still required limiting total to@35 or you would risk light high rpm ping on a hot day-hot water temp as it approached 5000 rpm. That's a whole different curve than if setup for 87 or less.
20 initial allowed hot starts without kickback or to slow cranking. 22 was ok when motor was below warmup.
I put timing back to a "normal" 12 initial 36 total in by 2500 and convinced Deb her motor could run the cheap gas with no issue.

So...start with finding your motors "happy" initial advance for hot(heat soaked) starts. Keep your unboosted advance total "normal" . Pull timing as motor gets into boost. You'll probably need no more than 24-27 degrees final timing boosted at peak rpm.

[blueghoast]

Originally Posted by BruceWilkie

Start with less and work your way up . Keep in mind that unboosted your running a low compression motor on premium fuel! !!

Deb's 406 originally had 6x-8 heads. Ran fine even on 85 octane from the reservation pump. On 93 premium it notably felt slower. On 93 advancing to 20 initial brought response back but still required limiting total to@35 or you would risk light high rpm ping on a hot day-hot water temp as it approached 5000 rpm. That's a whole different curve than if setup for 87 or less.
20 initial allowed hot starts without kickback or to slow cranking. 22 was ok when motor was below warmup.
I put timing back to a "normal" 12 initial 36 total in by 2500 and convinced Deb her motor could run the cheap gas with no issue.

So...start with finding your motors "happy" initial advance for hot(heat soaked) starts. Keep your unboosted advance total "normal" . Pull timing as motor gets into boost. You'll probably need no more than 24-27 degrees final timing boosted at peak rpm.

Good info thanks. We did go out last night and I raced a guy 1/8 mile.
Never checked plugs until I got back home. Acording to the plugs
It needed more timing and looked a little rich yet, But that was after
the drive home. So- there is a local place by my area I'm going to make
A pass and I'll read the plugs right after the run. That will give me better
Information on my next step. All you guys have been a lot of help.
I'll let you know what I find out on the next pass I do. Thanks Again.

GT.

[blueghoast]

We went out and did some racing last night, I didn't change any thing
And the car performed great. Checked the plugs after run and they
look pretty darn close. Timing is a bit slow but the car is working great
So I'm going to leave it alone for now. I am going to do a gear change.
Ether a 3:23 or 3:42. The car pulls hard and there's no issues, So it's time
to just have fun with it for a while. Thanks again all you've been a lot of help.
The 3:73 gear is just a little to much for it as this thing makes so much torqe.
The converter is great with no slippage. Sorry bout stealing your post but
Man what a source of info.

GT.

[er455]

Originally Posted by blueghoast

We went out and did some racing last night, I didn't change any thing
And the car performed great. Checked the plugs after run and they
look pretty darn close. Timing is a bit slow but the car is working great
So I'm going to leave it alone for now. I am going to do a gear change.
Ether a 3:23 or 3:42. The car pulls hard and there's no issues, So it's time
to just have fun with it for a while. Thanks again all you've been a lot of help.
The 3:73 gear is just a little to much for it as this thing makes so much torqe.
The converter is great with no slippage. Sorry bout stealing your post but
Man what a source of info.

GT.

Glad to hear it .. No worries on stealing my post , It helps me as well and I welcome anyone to chime in and comment on any of my posts ...I would go with the 3.23 . I have a 3.08 gear in mine with 28” tall tire and love it ...pulls like a freight train on top end .

[blueghoast]

Originally Posted by er455

Glad to hear it .. No worries on stealing my post , It helps me as well and I welcome anyone to chime in and comment on any of my posts ...I would go with the 3.23 . I have a 3.08 gear in mine with 28” tall tire and love it ...pulls like a freight train on top end .

Yeah that's prob what I'll do 3:23, Cause all the class races I'll be running
call's for a 28-inch tire. Thanks

GT.

[blueghoast]

Changed gear from 3.73 to 3.42 WOW What a difference that made.
I knew it would some but not like this. Thinking about the 3.23 yet.
Gona wait for a while and have some fun with this set-up for now.
The car is working great and running strong and not breaking or hurting
anything, So I'm going to enjoy it for now.

Thanks for all the info guy's.

GT.

[er455]

Cool I am waiting to go to the track to see if my 3.08 gear with a 28 “ tall tire is going to work before I swap to a 3.23 , they are so close that I don’t know if it worth doing ....

[ponjohn]

Originally Posted by blueghoast

Changed gear from 3.73 to 3.42 WOW What a difference that made.
I knew it would some but not like this. Thinking about the 3.23 yet.
Gona wait for a while and have some fun with this set-up for now.
The car is working great and running strong and not breaking or hurting
anything, So I'm going to enjoy it for now.

Thanks for all the info guy's.

GT.

How do you stage the car..on a 2 step...how many pounds...etc?


Does it pull the same out of the hole with the 3.42?

[charlie66]

Originally Posted by blueghoast

Changed gear from 3.73 to 3.42 WOW What a difference that made.
I knew it would some but not like this. Thinking about the 3.23 yet.
Gona wait for a while and have some fun with this set-up for now.
The car is working great and running strong and not breaking or hurting
anything, So I'm going to enjoy it for now.

Thanks for all the info guy's.

GT.

Just remember the lower you go the more stress you're putting on the crank . Do you have a forged or cast crank?

[ponjohn]

Originally Posted by charlie66

Just remember the lower you go the more stress you're putting on the crank . Do you have a forged or cast crank?

Because the turbos are loaded better?

[Tom Vaught]

Originally Posted by ponjohn

Because the turbos are loaded better?

Correct, Higher load due to the driveline providing less multiplication. Higher load = more exhaust mass flow thru the engine. More Mass flow the turbos can move more air thru the compressor side of the turbo. The two wheels are connected together by a common shaft (for non Turbo readers).

That being said, compared to a 500 rpm increase in rpm NA or Boosted, the same crank at the original rpm will see basically the same stresses or slightly more but a higher HP and torque.

Tom V.